Magnetic cooling device and magnetocaloric module thereof

ABSTRACT

A magnetic cooling device is provided, including a magnetocaloric module and a magnetic unit. The magnetocaloric module includes a bed, a first magnetocaloric material, a second magnetocaloric material and a thermal insulator. The first magnetocaloric material is disposed in the bed. The second magnetocaloric material is disposed in the bed, wherein the Curie Temperature of the second magnetocaloric material is greater than the Curie Temperature of the first magnetocaloric material. The thermal insulator is disposed between the first and second magnetocaloric materials to insulate heat conduction between the first and second magnetocaloric materials. The magnetic unit is coupled to the magnetocaloric module, wherein the magnetic unit reciprocally applies different magnetic fields to the first and second magnetocaloric materials, wherein a heat transfer fluid flows through the first and second magnetocaloric to transfer heat from a low temperature end to a high temperature end of the magnetocaloric module.

CROSS REFERENCE TO RELATED APPLICATIONS

This Application claims priority of Taiwan Patent Application No. 100139499, filed on Oct. 31, 2011, the entirety of which is incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a magnetic cooling device, and in particular relates to a magnetic cooling device and a magnetocaloric module with different magnetocaloric materials.

2. Description of the Related Art

Magnetic cooling devices do not need refrigerants and condensers, and have a simple structure, and produces less noise. Additionally, magnetic cooling devices consume less energy and maintenance costs are low, which are important research areas in refrigeration technology.

With reference to FIG. 1, in pages 1327-1331, volume 27 of the International Journal of Refrigeration, an active magnetic regeneration (AMR) is disclosed, which has four different magnetocaloric materials (Gd_(0.92)Y_(0.08)

Gd_(0.84)DY_(0.16)

Gd_(0.87)DY_(0.13)

Gd_(0.89)Dy_(0.11)) serially arranged from a low temperature end C to a high temperature end H, wherein each magnetocaloric material has a different Curie Temperature. With the serially arranged magnetocaloric materials, a working temperature range of the magnetic cooling device is increased, and refrigerating temperature of the magnetic cooling device is lowered.

However, the Curie Temperature of a magnetocaloric material is the best working temperature of the magnetocaloric material. When different magnetocaloric materials are serially arranged, heat is conducted along a serial direction between the magnetocaloric materials (along central axis A in FIG. 1), such that a temperature gradient therefore drops, and efficiency of the magnetic cooling device is decreased.

BRIEF SUMMARY OF THE INVENTION

The embodiment of the invention provides a magnetic cooling device. The magnetic cooling device includes a magnetocaloric module and a magnetic unit. The magnetocaloric module includes a bed, a first magnetocaloric material, a second magnetocaloric material and a thermal insulator. The first magnetocaloric material is disposed in the bed. The second magnetocaloric material is disposed in the bed, wherein the Curie Temperature of the second magnetocaloric material is greater than the Curie Temperature of the first magnetocaloric material. The thermal insulator is disposed between the first and second magnetocaloric materials to insulate heat conduction between the first and second magnetocaloric materials. The magnetic unit is coupled to the magnetocaloric module, wherein the magnetic unit reciprocally applies different magnetic fields to the first and second magnetocaloric materials, wherein a heat transfer fluid flows through the first and second magnetocaloric to transfer heat from a low temperature end to a high temperature end of the magnetocaloric module.

In one embodiment, the thermal insulator has a chamber, and the chamber is a vacuum or filled with gas.

In one embodiment, the thermal insulator comprises Aerogel.

In one embodiment, the thermal insulator comprises POM.

In one embodiment, the thermal insulator comprises Teflon.

In one embodiment, the thermal insulator comprises Asbesto.

In one embodiment, at least one of the first and second magnetocaloric materials comprises gadolinium or gadolinium alloy.

In one embodiment, at least one of the first and second magnetocaloric materials comprises yttrium alloy or dysprosium alloy.

In one embodiment, at least one of the first and second magnetocaloric materials comprises manganese alloy or lanthanum alloy.

In one embodiment, the magnetic unit is moved relative to the magnetocaloric module.

In one embodiment, the first and second magnetocaloric materials are serially arranged along a central axis of the magnetocaloric module, and the heat transfer fluid passes through the first and second magnetocaloric materials along the central axis.

The embodiment of the invention further provides a magnetocaloric module, disposed in a magnetic cooling device, wherein a magnetic unit of the magnetic cooling device reciprocally applies different magnetic fields to the magnetocaloric module. The magnetocaloric module comprises a bed, a first magnetocaloric material, a second magnetocaloric material and a thermal insulator. The first magnetocaloric material is disposed in the bed. The second magnetocaloric material is disposed in the bed, wherein the Curie Temperature of the second magnetocaloric material is greater than the Curie Temperature of the first magnetocaloric material. The thermal insulator is disposed between the first and second magnetocaloric materials to insulate heat conduction between the first and second magnetocaloric materials, wherein a heat transfer fluid flows through the first and second magnetocaloric to transfer heat from a low temperature end to a high temperature end of the magnetocaloric module.

A detailed description is given in the following embodiments with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:

FIG. 1 shows a conventional magnetocaloric module;

FIG. 2 shows a magnetic cooling device of an embodiment of the invention and a magnetocaloric module thereof; and

FIG. 3 shows a magnetocaloric module of another embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims.

FIG. 2 shows a magnetic cooling device 100 of an embodiment of the invention. The magnetic cooling device 100 comprises a magnetocaloric module 10 and a magnetic unit 20 (for example, magnet or electromagnet). The magnetic unit 20 is disposed around the magnetocaloric module 10, and reciprocally applies different magnetic fields to the magnetocaloric module 10. As shown in FIG. 2, the magnetocaloric module 10 has a bed 11, a first magnetocaloric material M1, a second magnetocaloric material M2 and a thermal insulator 12. The first magnetocaloric material M1 and the second magnetocaloric material M2 are disposed in the bed 11. The thermal insulator 12 is disposed between the first magnetocaloric material M1 and the second magnetocaloric material M2. In this embodiment, a gap between the first magnetocaloric material M1 and the second magnetocaloric material M2 can be filled with the thermal insulator 12. Additionally, in a modified example, through holes or porous structures can be formed inside the thermal insulator 12 allowing a heat transfer fluid to flow therethrough. For example, the thermal insulator 12 can be made of Asbesto, Teflon, Polyoxymethylene (POM) or Aerogel to prevent heat from being conducted between the first magnetocaloric material M1 and the second magnetocaloric material M2.

When the magnetic cooling device 100 is working, the magnetic unit 20 is reciprocally rotated or moved relative to the magnetocaloric module 10 to apply different magnetic fields to the first magnetocaloric material M1 and the second magnetocaloric material M2 and to change the temperature of the first magnetocaloric material M1 and the second magnetocaloric material M2 in a particular frequency. In the embodiment of the invention, the Curie Temperature of the second magnetocaloric material M2 is greater than the Curie Temperature of the first magnetocaloric material M1. By serially arranging the first magnetocaloric material M1 and the second magnetocaloric material M2, a working temperature range of the magnetic cooling device is increased, and a refrigerating temperature of the magnetic cooling device is lowered. As shown in FIG. 2, the heat transfer fluid enters the magnetocaloric module 10 through a low temperature end 101 (left side of the magnetocaloric module 10) thereof, travels through the first magnetocaloric material M1 and the second magnetocaloric material M2 along the central axis A, and exits the magnetocaloric module 10 through a high temperature end 102 (right side of the magnetocaloric module 10) thereof. Heat is moved from the low temperature end 101 to the high temperature end 102 by the heat transfer fluid to provide a refrigerating function.

In the embodiment of the invention, by the heat insulator 12 disposed between the first magnetocaloric material M1 and the second magnetocaloric material M2, heat is prevented from being conducted between the first magnetocaloric material M1 and the second magnetocaloric material M2 along the central axis A, such that the temperature gradient is prevented from dropping, and efficiency of the magnetic cooling device is improved.

FIG. 3 shows a magnetocaloric module 10 of another embodiment of the invention. As shown in FIG. 3, the magnetocaloric module 10 has a bed 11, a first magnetocaloric material M1, a second magnetocaloric material M2 and a thermal insulator 13. The thermal insulator 13 is a hollow structure and is disposed between the first magnetocaloric material M1 and the second magnetocaloric material M2. For example, the thermal insulator 13 can be made of Asbesto, Teflon, POM, Aerogel or other thermal insulating materials. Additionally, the thermal insulator 13 can include meshed or porous structures allowing the heat transfer fluid to flow therethrough. A chamber 130 is formed inside the thermal insulator 13 to prevent heat from being conducted between the first magnetocaloric material M1 and the second magnetocaloric material M2.

The chamber 130 inside the thermal insulator 13 can be sealed, which is a vacuum or filled with gas (for example, air) to prevent heat from being conducted between the first magnetocaloric material M1 and the second magnetocaloric material M2, and to prevent a temperature gradient from dropping. The efficiency of the magnetic cooling device is therefore improved. The first magnetocaloric material M1 and the second magnetocaloric material M2 can be made of gadolinium, gadolinium alloy, yttrium alloy, dysprosium alloy, manganese alloy, lanthanum alloy or other magnetocaloric materials.

The invention provides a magnetic cooling device and magnetocaloric module thereof, wherein a plurality of different magnetocaloric materials are disposed in the magnetocaloric module, and thermal insulator is disposed between the magnetocaloric materials to prevent heat conduction therebetween. The thermal insulator slightly increases the dimension of the magnetocaloric module, but sufficiently prevents a temperature gradient from dropping. The magnetocaloric module of the invention can be widely utilized in various magnetic cooling devices.

Use of ordinal terms such as “first”, “second”, “third”, etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements.

While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements. 

1. A magnetic cooling device, comprising: a magnetocaloric module, comprising: a bed; a first magnetocaloric material, disposed in the bed; a second magnetocaloric material, disposed in the bed, wherein the Curie Temperature of the second magnetocaloric material is greater than the Curie Temperature of the first magnetocaloric material; and a thermal insulator, disposed between the first and second magnetocaloric materials to insulate heat conduction between the first and second magnetocaloric materials; and a magnetic unit, coupled to the magnetocaloric module, wherein the magnetic unit reciprocally applies different magnetic fields to the first and second magnetocaloric materials, wherein a heat transfer fluid flows through the first and second magnetocaloric to transfer heat from a low temperature end to a high temperature end of the magnetocaloric module.
 2. The magnetic cooling device as claimed in claim 1, wherein the thermal insulator has a chamber, and the chamber is a vacuum or filled with gas.
 3. The magnetic cooling device as claimed in claim 1, wherein the thermal insulator comprises Aerogel.
 4. The magnetic cooling device as claimed in claim 1, wherein the thermal insulator comprises POM.
 5. The magnetic cooling device as claimed in claim 1, wherein the thermal insulator comprises Teflon.
 6. The magnetic cooling device as claimed in claim 1, wherein the thermal insulator comprises Asbesto.
 7. The magnetic cooling device as claimed in claim 1, wherein at least one of the first and second magnetocaloric materials comprises gadolinium or gadolinium alloy.
 8. The magnetic cooling device as claimed in claim 1, wherein at least one of the first and second magnetocaloric materials comprises yttrium alloy or dysprosium alloy.
 9. The magnetic cooling device as claimed in claim 1, wherein at least one of the first and second magnetocaloric materials comprises manganese alloy or lanthanum alloy.
 10. The magnetic cooling device as claimed in claim 1, wherein the magnetic unit is moved relative to the magnetocaloric module.
 11. The magnetic cooling device as claimed in claim 1, wherein the first and second magnetocaloric materials are serially arranged along a central axis of the magnetocaloric module, and the heat transfer fluid passes through the first and second magnetocaloric materials along the central axis.
 12. A magnetocaloric module, disposed in a magnetic cooling device, wherein a magnetic unit of the magnetic cooling device reciprocally applies different magnetic fields to the magnetocaloric module, comprising: a bed; a first magnetocaloric material, disposed in the bed; a second magnetocaloric material, disposed in the bed, wherein the Curie Temperature of the second magnetocaloric material is greater than the Curie Temperature of the first magnetocaloric material; and a thermal insulator, disposed between the first and second magnetocaloric materials to insulate heat conduction between the first and second magnetocaloric materials, wherein a heat transfer fluid flows through the first and second magnetocaloric to transfer heat from a low temperature end to a high temperature end of the magnetocaloric module.
 13. The magnetocaloric module as claimed in claim 12, wherein the thermal insulator has a chamber, and the chamber is a vacuum or filled with gas.
 14. The magnetocaloric module as claimed in claim 12, wherein the thermal insulator comprises Aerogel.
 15. The magnetocaloric module as claimed in claim 12, wherein the thermal insulator comprises POM.
 16. The magnetocaloric module as claimed in claim 12, wherein the thermal insulator comprises Teflon.
 17. The magnetocaloric module as claimed in claim 12, wherein the thermal insulator comprises Asbesto.
 18. The magnetocaloric module as claimed in claim 12, wherein at least one of the first and second magnetocaloric materials comprises gadolinium or gadolinium alloy.
 19. The magnetocaloric module as claimed in claim 12, wherein at least one of the first and second magnetocaloric materials comprises yttrium alloy or dysprosium alloy.
 20. The magnetocaloric module as claimed in claim 12, wherein at least one of the first and second magnetocaloric materials comprises manganese alloy or lanthanum alloy.
 21. The magnetocaloric module as claimed in claim 12, wherein the magnetic unit is moved relative to the magnetocaloric module.
 22. The magnetocaloric module as claimed in claim 12, wherein the first and second magnetocaloric materials are serially arranged along a central axis of the magnetocaloric module, and the heat transfer fluid passes through the first and second magnetocaloric materials along the central axis. 